Process of separating suspended pulp.



W. HOSKINS;

PROCESS OF SEPARATING SUSPENDED PULP.

APPLICATION FILED OCT. 15, 1915 Patented May 15, 1917.

WILLIAM HosKIN's, or QHICAYGVO', 1ILLINQIS.

rnocnss or snrnnnwmesnsrnmmn PULP, f

Specification of Letters Patent.- Patented-May 15, 1917.

Application filed October 15, 1915. Serial No. 56,1G1.

To all whom it may concern:

Be it known that I,:WILLIAM HOSKINS, a citizen of the United States, residing at Chicago, in the county of Cook'and State of i Illinois, have invented a new'and useful Imof Separating Susprovement Processes pended Pulp, specification.

My invention relates to the art of recovering suspended pulp from liquids carrying the same. More particularly, the invention is applicable to paper pulp mills in which the waste-water contains sulfite liquor and a certain proportion of finely-divided pulp held in suspension The specific gravity of these wetted particles of pulp isso close to that of the water that it is exceedingly difficult to efi'ect their precipitation in any practical form of settling tank. Instead of attempting to precipitate this pulp, I therefore propose to separate the same from the waste-water by causing the pulp to rise to the surface and remain there as a scum or floating stratum which may conveniently be skimmed oif.

An apparatus suitable for efi'ecting this result is illustrated by the accompanying drawing in which there is shown a body of the waste-liquor indicated by the numeral 1 and carrying in suspension particles of finely-divided pulp, 2. The liquor may be held in any desired form of tankbut it is not necessary that anyspecial structure be of which the following is a provided, the usual open channels which drain oif theQwaste-liquor being sufiicient if they are large enough in cross-section to limit the velocity to a reasonable figure. In the drawing, the numeral 3 designates the bottom of such an open c hannel, the direction offiow of the liquid in the channel being shown by the arrow therein. At the outer end of the channel there is provided a dam 4: of any suitable form extending above the surface of the liquid and having an 5 aperture 5 near the bottom through which the'liquid flows. I 1

The channel bottom 3 is covered with a thin layer of natural limestone 6 which may extend up the channel away from the dam for any desired distance, depending upon the width of the channel, and the velocity and depth of the liquid booly therein, as

will later appear.

The liquid body being thus dammed at its upper surface and contacting with abottom of limestone, the following action will take place: the sulfites' contained in the-liquor will react upon the limestone to liberatecarbon dioxid gas, the bubbles of which as formed will rise through the liquid body and in their upward passage will attach themselves to the suspended pulp particles,

which will thereby be carried upwardly to i the surface, forming a scum or surface stratum very rich in pulp. This scum will fioatdownward until it is arrested by the dam, and may be skimmed off at that point or pumped or run ofi or removed by any desired means. i

From the foregoing it is apparent that the purposes: of the present invention may best be fulfilled where the body of liquid is relatively quiescent, that is, where the velocity of the water is low enough to permit each portion of it to remain in contact with the limestone long enough to effect the de sired generation of gas and flotation of the suspended matter by this gas as it rises through the liquid body.

While I have illustrated and described in some detail one application of my new process and the means for applying the process,

these details are illustrative only, and for the purpose of making my invention more clear and I do not regard the invention as limited to such details of either construction or' use, except in sofar as I have included the same within the t rms of the following claims.

-What I regard as new anddesire to secure by Letters Patent is i 1. The method of separating from a liquid-body consisting of or containing in solution a chemically-active constituent, paper pulp suspended therein, which consists in bringing the liquid into contact with an immersed solid of a character which is acted upon by the said constituent to liberate gases, whereby the liberated gases rise from the immersed solid and in passing upwardly carry with them to the surface the said suspended pulp to form of the latter a scum or surface stratum, and removing the said scum or surface stratum.

2. The method of separating from an acid liquor paper pulp suspended therein, which consists in bringing theliquor into contact with an immersed carbonate which is attacked by the said acid to liberate carbon dioxid, whereby the carbondioxid will rise fthrofigh the liquor and carry to the surfaee l nersed limestone, ahd perhbving the resultthereof the'suspended pulp, forming offthe ant pulp-carrying surfece-stmtum. latter a surface-stratum or scum, and rempv: ing the'said scum.

" 5 3 The method of separating suspended e In piesehce 'ofv-v,

pulp from sulfite waste-waterswhich con-' A; G. Freeing; sists in' passing the said waters o er'. im- K. ONBILL.

' WILLIAM HO'SKINS. 

